1. Field of the Invention
The present invention relates to a programmable industrial controller configured to measure the thickness of a strip of material in a press.
2. Description of the Related Art
Traditionally, progressive die machines include an upper die that is reciprocally moveable with respect to the lower die. A motor imparts rotational motion to the output shaft that, in turn, rotates a eccentrically-mounted pin on a concentrically-mounted plate on an output shaft, thereby tracing a circular path. The rotational motion, in turn, results in a ram mounted on an upper surface of the die to move reciprocally with respect to the lower die.
A rotation of the output shaft of the motor is a xe2x80x9cstrokexe2x80x9d of the machine that ranges from 0 to 360 degrees. The point at which the pin on the plate of the motor output shaft is located at the uppermost vertical position with respect to the plate is the xe2x80x9czero positionxe2x80x9d or xe2x80x9ctop dead centerxe2x80x9d. At the top dead center position, the upper die is positioned with the greatest extent above the lower die. The point at which the pin on the plate of the motor output shaft is located adjacent to the lowermost vertical position with respect to the plate is the xe2x80x9c180 degree positionxe2x80x9d. In the 180 degree position, the upper die is positioned adjacent to the lower die and this is the position whereby the forming operations are performed on the web. Between the 0 and 180 degree positions, the upper die is lowered with respect to the lower die and between the 180 and 360 degree positions, the upper die is raised with respect to the lower die.
The upper and lower dies cooperate to define several forming stations therein. Each forming station includes an individual forming tool and a die which are configured and dimensioned so that a particular predetermined operation can be performed on the web fed between the upper and lower dies. The web is typically an elongated strip of material provided as a feedable supply adjacent the machine, such as on a spool. The progressive die machine typically includes a feeding apparatus mounted adjacent the lower die which sequentially advances the web between the upper and lower dies and through each of the forming stations therein.
The number of forming stations is determined by the number of forming operations necessary to form a desired part. A portion of each of the forming tools is located on the upper die and are driven in unison in reciprocal fashion by the ram. Therefore, a forming operation is performed at each forming station during each stroke of the ram.
Following each stroke, the web is advanced so that each portion of the web is positioned within the next successive forming station in the machine. When a portion of the web has passed each forming station in the progressive die machine, a desire part is formed. The last station in the machine typically includes a severing tool and a discharge chute. The severing tool cuts the formed part from the web so that the formed part can fall into the discharge chute and be accumulated therein.
Typically, both lamination and progressive die machines are plagued with many uncontrollable problems resulting in formed parts that are not within a certain tolerance that have to be thrown away. In many cases, the tolerances that the parts must fall within are of a critical importance and a part that falls outside of the tolerances can cause a catastrophic failure in the system or machine in which the part is ultimately installed. In particular, lamination dies often experience problems due to variations in the thickness of the web material from which the parts are formed.
Due to the difficulties associated with accurately measuring the thickness of the web material to ensure that a part is going to be within a certain tolerance prior to punching that part, there is a need for measurement system that is configured to continuously monitor and measure the thickness of the web of material being fed into the press.
Accordingly, one object of this invention is to provide a material measurement system in a press including a press machine, a first material measurement sensor, a second material measurement sensor, and a press controller. The press machine includes a lower die coupled to an upper die and the lower die includes a top surface supporting a strip of material to be formed into a part after a stripper plate coupled to the upper die contacts the strip of material. The first material measurement sensor has a first end opposite a second end, and a center axis therebetween. The first end is adjacent to a top surface of the strip of material and the first sensor generates a first measurement signal corresponding to the thickness of the strip of material. The second material measurement sensor includes a first end opposite a second end, and a center axis therebetween. The first end is adjacent to a bottom surface of the strip of material and the center axis of the first sensor aligns with the center axis of the second sensor. The second sensor generates a second measurement signal corresponding to the thickness of the strip of material. The press controller is coupled to the press machine, the first sensor, and the second sensor. The controller processes the first and the second measurement signals, compares the first and the second measurement signals to a predetermined threshold value, and generates a command signal to the press machine to continue or stop forming the part based on the first and the second measurement signals.
Another object of this invention is to provide a material measurement system in a press including a press machine, a first material measurement sensor, a second material measurement sensor, and a press controller. The press machine includes a lower die coupled to an upper die and the lower die includes a top surface supporting a strip of material to be formed into a part after a stripper plate coupled to the upper die contacts the strip of material. The first material measurement sensor has a first end opposite a second end, and a center axis therebetween. The first end is adjacent to a top surface of the strip of material, but not in contact with the top surface of the strip of material. The first sensor generates a first measurement signal corresponding to the thickness of the strip of material. The second material measurement sensor includes a first end opposite a second end, and a center axis therebetween. The first end is adjacent to a bottom surface of the strip of material and the center axis of the first sensor aligns with the center axis of the second sensor. The first end is not in contact with the bottom surface of the strip of material. The second sensor generates a second measurement signal corresponding to the thickness of the strip of material. The press controller is coupled to the press machine, the first sensor, and the second sensor. The controller processes the first and the second measurement signals, compares the first and the second measurement signals to a predetermined threshold value, and generates a command signal to the press machine to continue or stop forming the part based on the first and the second measurement signals.
Yet another object of this invention is to provide a material measurement system in a press including a press machine, a material measurement sensor, and a press controller. The press machine includes a lower die coupled to an upper die and the lower die includes a top surface supporting a strip of material to be formed into a part after a stripper plate coupled to the upper die contacts the strip of material. The material measurement sensor has a first end opposite a second end, and the first end is adjacent to the strip of material. The sensor generates a measurement signal corresponding to the thickness of the strip of material. The press controller is coupled to the press machine and the sensor. The controller processes the measurement signal, compares the measurement signal to a predetermined threshold value, and generates a command signal to the press machine to continue or stop forming the part based on the measurement signal.